[dpdk-stable] [PATCH v4] net: fix Intel-specific Prepare the outer IPv4 hdr for checksum

[Mohsin Kazmi <mohsin.kazmi14@gmail.com>]

Preparation of the headers for the hardware offload
misses the outer IPv4 checksum offload.
It results in bad checksum computed by hardware NIC.

This patch fixes the issue by setting the outer IPv4
checksum field to 0.

Fixes: 4fb7e803eb1a ("ethdev: add Tx preparation")
Cc: stable@dpdk.org

Signed-off-by: Mohsin Kazmi <mohsin.kazmi14@gmail.com>
Acked-by: Qi Zhang <qi.z.zhang@intel.com>
Acked-by: Olivier Matz <olivier.matz@6wind.com>
---
v4:
   * Update the commit message

v3:
   * Update the conditional test with PKT_TX_OUTER_IP_CKSUM.
   * Update the commit title with "Intel-specific".

v2:
   * Update the commit message with Fixes.

 lib/net/rte_net.h | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/lib/net/rte_net.h b/lib/net/rte_net.h
index 434435ffa2..42639bc154 100644
--- a/lib/net/rte_net.h
+++ b/lib/net/rte_net.h
@@ -125,11 +125,22 @@ rte_net_intel_cksum_flags_prepare(struct rte_mbuf *m, uint64_t ol_flags)
 	 * Mainly it is required to avoid fragmented headers check if
 	 * no offloads are requested.
 	 */
-	if (!(ol_flags & (PKT_TX_IP_CKSUM | PKT_TX_L4_MASK | PKT_TX_TCP_SEG)))
+	if (!(ol_flags & (PKT_TX_IP_CKSUM | PKT_TX_L4_MASK | PKT_TX_TCP_SEG |
+			  PKT_TX_OUTER_IP_CKSUM)))
 		return 0;
 
-	if (ol_flags & (PKT_TX_OUTER_IPV4 | PKT_TX_OUTER_IPV6))
+	if (ol_flags & (PKT_TX_OUTER_IPV4 | PKT_TX_OUTER_IPV6)) {
 		inner_l3_offset += m->outer_l2_len + m->outer_l3_len;
+		/*
+		 * prepare outer IPv4 header checksum by setting it to 0,
+		 * in order to be computed by hardware NICs.
+		 */
+		if (ol_flags & PKT_TX_OUTER_IP_CKSUM) {
+			ipv4_hdr = rte_pktmbuf_mtod_offset(m,
+					struct rte_ipv4_hdr *, m->outer_l2_len);
+			ipv4_hdr->hdr_checksum = 0;
+		}
+	}
 
 	/*
 	 * Check if headers are fragmented.
-- 
2.17.1